HARD And SOFT States

A monitoring system that sends notifications as soon as it detected that something went wrong would send a LOT of notifications. When in reality there may be a logical reason why a service failed to be checked, like it simply timed out sending a response. The next time the service is checked it responded correctly and everything was OK, there was really no reason to send a notification.

Nagios will check a host or service every X minutes and if there is a state change then it will re-check Y times Z minutes apart.

check_interval Xretry_interval Zmax_check_attempts Y

The max_check_attempts directive allows you to define when you think Nagios should treat this as a real problem. While it's determining this, these are called SOFT states.